Fuel supply system for internal combustion engines



Oct. 10,1961 E. A. JOHNSON 3,003,753

FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 2, 1958 4 Sheets-Sheet 1 INVENTOR. ELDON A. JOHNSON AITORNEY Oct. 10, 1961 E. A. JOHNSON FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 2, 1958 4 Sheets-Sheet 2 INVENTOR. ELDON A. JOHNSON ATTORNEY Oct. 10, 1961 E. A. JOHNSON SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 2, 1958 4 Sheets-Sheet 3 FIGS.

.ELDON A.JOHNSON ATTORNEY Oct. 10, 1961 E. JOHNSON 3,003,753

FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 2, 1958 4 Sheets-Sheet 4 /4 INVENTOR.

ELDON A. JOHNSON ATTQBNEYv United v States Patent dustries, Incorporated, New York, N.Y., a corporation of New Jersey 1 Filed June 2, 1958, Ser. No. 739,267

Claims. 7 (Cl. 261-36) This invention relates to fuel systems for internal combustion engines, and more particularlyto a system for maintaining a more nearly constant head or. constant fuel level in a Carburetor fuel bowl of an automotive vehicle engine.

Carburetors now in general use for the purpose have a float operated fuel inlet needle valve for maintaining a constant head of fuel on the metering jets of the car'- buretor by limiting the rate of fuel supply by changes in fuel level. Such a structure, although'theoretically simple, presents a difiicult engineering problem for each different carburetor. It will be readily recognized that the needle valve size and construction, float size, lever length, and float bowl configuration and size, all have variable related requirements, one to the other,'which must be compromised to arrive at a dependable operable structure with not only the necessary fuel capacity, but with some reserve capacity, in order to successfully handle mixtures of gas and fuel, or gas alone; otherwise, the fuel supply system will be prone to vapor lock. This refers, of course, to the part of the fuel supply system feeding fuel to the inlet needle valve. Every carburetor has the necessary vents for disposing of these vapors and gases once they reach the carburetor fuel bowl. These vents do not, however, have any substantial effect upon the operation of the remainder of the system supplying the fuel to the carburetor fuel bowl.

These variables in the float valve design determine the minimum size for the float chamber and this size may be ineflicient, to some degree, to maintain a constant head of fuel over the metering jets of the carburetor, especially when thevehicle. is tilted, accelerated, or decelerated-in a linear path, or experiences angular accelerations. It seems that the smaller-the fuel bowl or fuel containing chamber in the carburetor, the more efiicient it becomes in this respect.- For this reason, reconsideration has been given the so-called"floatless carburetor wherein the overflow chamber is smaller and such forces as'above described have less effect upon the primary function of head regulation. This type ofcarburetor in. itself involves some of the problems above enumerated, 'butto a lesser degree, and forms a part of a different type of fuel supply system than now in' use because of the necessity of recirculating the fuel to. and from the fuel bowl.

Some thought has been given to'this systemheretofore, but it does not appear that those concerned understood the problems thoroughly.

According to this invention, the fuel head in the carburetor fuel bowl is maintained by a continuous flow of fuel intoan overflow chamber of'comparatively small capacity. The rate of flow is preferably held to some extent proportional to the rate of fuel consumption by the engine, and the fuel level is controlled in this chamber. by a weir which is arranged to spill fuel above the level 3,003,753 Patented Oct. 10, 1961 be. This sump or sumps have one or more outlets which are float valve controlled. The float valves used in the sumps are novel, both in construction and operation, since they'must open against the suction created by the fuel pump. Preferably, the float valve is unrestrained, with freedom to move in both angular and bodily directions for the purpose ofmore readily performing its intended function to open and close an outlet subject to pump suction.

Thisfuel system also includes a tank, an engine driven fuel pump, a tank supply line between the two, recirculating fuel lines between the pump and the carburetor, and possibly an automatic selector valve to maintain fuel in the recirculating fuel lines by switching the inlet of the pump from its connection with the'recirculation system or circuit to a by-pass extending therearound and connected in parallel with the fuel tank.

It is one of the objects of this invention to provide a recirculating fuel system for an internal combustion engine.

It isone of the objects of this invention to maintain a substantially constant head of fuel in a carburetor.

It is one of the objects of this invention to eliminate 1 air and fuel-vapors from the fuel system.

of the weir into a sump orpair of sumps, as the case may 1 It is one of the objects of this'invention to eliminate long fuel return lines extending to the tank. 7

It is one of the objects of this invention 'to eliminate restrictions of the inlet to the carburetor fuel bowlfand thus avoid one of the contributing factors to vapor lock.

It is one of the objects of this invention to eliminate the effect of ram pressure on the fuel supply system.

It is one of the objects of this invention to eliminate the effect of surge within the carburetor on the fuel metering.-

It is one of the objects of this invention to prolong pump life by' relating the rate of pump delivery to the rate of fuel consumption by the engine.

The accompanying drawings illustrate several forms of the invention, in which:

FIG. 1 is an environmental view showing the fuel system of this invention applied to an automotive vehicle chassis.

FIG. 2 is an illustration of the carburetor and pump, together with their interconnecting fuel lines, all as shown in FIG. 1, With parts of the carburetor broken away and in section to illustrate the constructionwithin the fuel bowl.

FIG. 3 is a top plan view of the fuel bowl of the carburetor illustrated in FIG. 2, With the fuel bowl cover removed.

FIG. 4 is a view illustrating the internal construction of the fuel pump in vertical section.

7 FIG. 5 is a fragmentary sectional view taken on two planes through the carburetor bowl to illustrate the action of the float valve.

FIG. 6 is a similar view to FIG. 5, illustrating a float valve in another operative position.

FIG. 7 is another modification of the fuel system shown in FIG. 2, using a selector valve with parts of the carburetor and selector valve in section to illustrate the construction. 7

FIG. 8 is a modified form of selector valve which may be substituted for that shown FIG. 7.

The following detailed description of the structure in the: drawings Should b falifi as illustrative only.

In FIG. 1 there is illustrated an automotive chassis having any suitable internal combustion engine such as 11 mounted in the forward portion thereof, and a fuel supply tank 12 mounted at the rear. The tank may have a filler spout such as 13. Tubing 14 extends from the fuel tank 12 to a fuel pump 15 which is the mechanical type driven from the engine. The particular type of pump is not material to the invention nor is the manner in which the pump is driven, but for purposes of illustration the pump here can be considered ofthe kind such as shown in the patent to Coffey, 2,803,265, of August 20, 1957,- or as shown in my copending application Serial No. 739,268, filed June 2-, I958.

Such pumps are usually driven from the engine and are mounted thereon toithis purpose.

According to this invention the fuel supply system; includes the line from the tank to the fuel pump 15 and a supply and return line extending to the carburetor. The supply line is 16 and the return line is 18, both of which are connected with the fuel metering device, in this case a carburetor 17. This fuel supply sy'ste'nr can be applied to any fuel metering device used on an internal combustion engine, and the carburetor is shown merely as an illustration of one formof such devices. 7 V I In the following paragraphs the modifications necessary to adapt the carburetor to this type of fuel supply system are described, but these modifications are not restricted to carburetors of a particular type or even carburetors as such. These modifications can also .be made in most fuel injection systems so as to supply the metering devices therein, and it might be added that the same advantages will be gained when the fuel supply system of this invention is applied to any of these devices for metering fuel for combustion in an internal combustion engine.

For purposes of illustration, applicant has shown a carburetor 17 suitably modified for use with this fuel supply system. The various details of carburetor construction are not material to this particular invention, and this description will be confined to a general identification of the carburetor elements and a more detailed description of the modifications in the fuel bowl necessary to adapt this type of carburetor to be used in this particular fuel supply system. It will be understood that the carburetor without these modifications in the float bowl and fuel bowl but with an ordinary float controlled constant level type of fuel chamber is a Carter BBD.

' Carburetor construction Turning now to FIGS. 2 and 3, the carburetor 17 generally indicated in FIG. 2 by the reference character 17 is, as above stated, a dual type having a pair of mixture conduits 19 and 20 disposed side by side, which turn have a cominon inlet in the air horn 2'2. Disposed in the inlet is a choke valve such as '24 which in turn controls the position of a fast idle acting as a throttle stop for the throttle linkage including 'a pivot'ed lever 26, link 27, and throttle lever 28. H

Throttle shaft 29 mounts a pair of throttles 30, one of which is shown, movements of the throttle lever 28 rotate the shaft .29 and the throttles 30 as well as an accelerating pump linkage including link 32, lever 33, and shaft 34. This in tum operates the piston or an accelerating pump located in a cylinder shown in FIG. 3. p

The carburetor has a fuel bowl generally indicated as 38, and within this fuel bowl are a pair of metering jets or orifices 39 and 10 which supply the 'fuel'noz'zl'es 41 and 42" located within boost venturi of a nozzle clustergeneral'ly indicated as 44. 7 7 e The throttle body of the carburetor has the usual idle adjusting screws 45, one of which is shown, and an 4 adjustably mounted throttle stop screw 36 threaded in a'lug integral" with the throttle body 37.

The throttle body 37 has suitably located stud receiving holes so as to secure the carburetor throttle body to the intake manifold of the engine 11 all as shown in FIG. 1. When so mounted, the fuel bowl 38 is at the front of the carburetor and the mixture coud uits are disposed transversely across the chassis and transversely to the axis of the crank shaft of the engine.

Carburetor float Irowl construction Turning now to the fuel bowl of this carburetor, it will be noted that the float and needle usually used have been eliminated, and in place thereof the metering jets 39 and 40 have been separated from the remainder of the fuel bowl or isolated within a small compact chamber defined by the weirs 46 and 47 and the partition 48 which forms a wall of the mixture conduits and the outside wall 49 of the fuel bowl. In FIG. 3 the carburetor has been shown with the air horn and float bowl cover removed so as to illustrate this arrangement. The weirs 46 and 47 extend longitudinally or lengthwise of the vehicle when the carburetor ismounted thereon, as shown in FIG. 1'. Consequently, rapid acceleration or deceleration will cause the fuel within the chamber 50 to spill over one or both of the weirs 46 and 47 transverse to the direction of travel of the motor vehicle into a pair of sumps 51 and 52. Also, it should be noted that cornering of the vehicle which is s'ufliciently violent will cause the spill-over of either the weir 46 or47 into the sumps so that at uo time will the level of the fuel within the chamber 50 exceed the level determined by the height' of the weirs 46 and 47.

Chamber 50 is supplied as through a connection 55 extending through the wall 49 of the fuel bowl and this connection in turn is controlled by a needle valve such as 56 operatedinto and out of, or within the metering restriction 57 in the fitting 55. Operation of the needle 56 is affected by a cam 58 operated from the pump shaft 34 by movement of the throttle from closed to open and back. It will be noted that, as the throttle opens, the needle 56 is withdrawn in the metering restriction, 55 so as to increase the size of the metering orifice with the increase in rate of tuel consumption of the carburetor so that the size of orifice 57 varies almost directly with the rate of fuel consumption of the engine.

The needle 56 need not actually close the restriction 57 and it is intended that when the throttle is partly open to full open the needle will have an effective opening much larger than the conventional needle valve seat.

Where two sumps are used such as 51 and 52 each has an outlet such as 60 and 61 interconnected by a cross passage 62 with a fuel return passage 63 controlled by a check valve 64. A check valve seat 65 is screwed into the passage and the passage suitably closed by a welch plug such as 66. Return passage 63 extends to a fitting 68. Supply fitting 55 connects with fuel hue 16 to the outlet of a pump generally indicated as 15 and return passage 63 is connected with the inlet of the pump by a fuel line 18 attached to the fitting 68' and to a T 71 which has two branches 72 and 73. Branch 72 connects with the inlet of the pump directly,'and branch 73 connects with fuel line 14 extending from the fuel tank.

The outlets 60 and 61 in the fuel sumps 51 and 52, respectively, are each identical and only one will be -'described.- The outlet '60, for ex-ample, located in a boss 75 which in turn has a valve seat 76 controlling at the inlet thereof. A float such as 78 mounts a ball valve such as 79 received in the seat 76 and the float 7-8 as an overhanging '80 extending beyond the ball valve and slightly spaced above the "surface or the boss oranabutment 75 when the valveisin closed position.

Operationof carburetor structure 1 As explained hereinafter, the operation of theengi'ne will produce delivery of fuel from the tank to the pump and from the pump through the line 16- past the metering restriction 57 and needle 56 into the constant level chamber 50 defined by the walls of the fuel bowl and the weirs 46 and 47. I

This explanation of operation will be limited to static conditions first, and then the effect of dynamic conditions will be discussed. Under static conditions with the engine operating at idle, needle 56 will to some extent re strict the flow of fuel through the line 16 from'the' pump 15. This is because the throttle is closed and the cam 58 is raised, pushing the needle 56 into the restriction 57. This feature has its own purpose, namely, to cut down the delivery from the fuel pump 15 and, therefore, increase the life of the pump 15.

- It is possible, of course, to dispense with this feature and leave the fitting 55 unrestricted, such as would be the case-if the throttle were wide open and the needle 56 with-' drawn at all times, but it has been discovered that operation of the'system is improved by the use of some limited metering at this point and for normal slow op'eration of the'engine and extending into theintermediate range of engine speed. With this metering present under these conditions the amount of delivery of pump 15 is limited and, as will be later discussed, thepump will not take a full stroke and therefore will not be continuously operating at maximum capacity thereby prolonging its life.

As the fuel is delivered past the needle 56 it fills the chamber 50 up to the level of the weirs 46 and 47 and, since the amount delivered to the chamber 50 is always in excess of carburetor requirements, fuel will continually spill over the top of the weirs into the sumps 51 and 52. As the fuel level rises in the sump, float 78 will rise with-the fuel, pivoting about the ball 79 until the overhang or extension portion '80 of the float 78 comes in contact with the upper surface of the boss 75. There is always some degree of suction in the return line 18 to the pump and consequently some degree of suction holding the 'ball valve 79 to its seat. When the pivoting of the floats 78 progresses to the point-where overhang 80 strikes the top of the surface of the boss 75, the ball 79 is pried loose from its seat 76, as shown in FIG. 5, and floats upon the surface of the liquid as shown in FIG. 6 thus opening the return passage 63 tothe pump.

As the level in the sump lowers, the float will settle until ball 79 again engages seat 76 closing the return passage 63. Theinternal contour of the sump cooperates to hold the float in alignment so that the valve 79 will strike the seat 76, and no external linkage or guides are required within the sump to facilitate engagement of the ball 76 on its seat. Thus the action of the float 78 permits afloat of much smaller size and provides a much simpler mechanism for controlling the flow of fuel from the sump back to the pump. The mechanism is simple and very eifective for this purpose and certainly represents a distinct advance'fr'om the production point of view. p 7 As ,will be subsequently explained, once the valve 79 closes, suction of the pump is concentrated to supply fuel from the tank to the line 16. On the other hand with the float 78 raised and valve'79 open the pump 15 willjbe' supplied with fuel from the sump rather than the tank. But under all conditions the lines extending to the. inlet of the pump 15 are maintained full of rue and it will be noted that the constant circulation of the fuel into and out of the fuel bowl releases any vapors in the fuel so that they can escape through the carburetor vent system which is not shown. v 7

Under dynamic conditions wherein thelfuel experiences the eflfect of accelerations due to operation of the motor vehicle, the overfiowch'amber 50'i s an effective means for maintaining a substantially constant fuel level or head on the metering jets 39 and 40 and therefore a uniform flow of fuel through the metering system of the carburetor to the engine. 'in spite of adverse dynamic conditions. 1 jIn the first place, thesize of the overflow chamber-50 is small when viewed in plan,- relative to its depth as viewed in elevation, whereby the surge of the fuel will have its least effect upon the fuel head on the jets. In the second place,

the weirs are disposed lengthwise of the vehicle sothat fore and aft surge of the fuel does not directly pass over the weirs but first strikes the end wall of the fuelbowls and then spills over. This minimizes the effect of fore and aft surges of fuel on thefuel head maintained.-

Y The fuel pump the aforesaid Coffeypatent isshown connected into the fuel supply system. Turning now to consider FIGS. 2 and 4, thefuel pump 15 has .a rocker arm housing such as in which is pivotly mounted a rocker arm 96 maintained in contact with an engine driven eccentric cam 97 by spring 98, It will be understood that this View is more or less schematic and cam ,97. is generally formed integral with thecam shaft of theengine. a v l 1 a Secured to the rocker armcasing 95 (FIG. 4) is a valve housing 99 containing an inlet valve 100 and a discharge valve 101. I 5- Pump 15 is of the diaphragm type and the diaphragm thereof 103 is secured between the'rocker arm casing 95 vand the valve housing 99 by-aseries of screws 104. Diaphragm 103 is supported by a pair of backing plates generally indicated .as 106 which in turn are firmly secured to a stem 107 operated in one direction by the rocker arm 96. A spring 110 suitably interposed between the rocker housing 95 and backingplates 106 powers the discharge stroke of the pump. It will be understood that in. this type oftpumpthe length of the discharge stroke produced by the spring llll-acting on the diaphragm .and backing plates 103 and 1 06'is 'primanly determined bythe discharge pressure in the 'discharge line from the pump. Against a normal head of pressure, say up .to three pounds, the pump operates at substantially full stroke and has its -maximuin capacity. On the other hand this type of pump, when working against a full head such .as, say five or-six pounds; *operates at a very limited stroke because the pressures under the diaphragm in the pumping chamber will not permit the spring 110to expand.

Pump 15 has an inlet connection 121 communicating with the inlet valve 100 and has a discharge connection communicating with the discharge valve 101 and all located in the valve body 99. The inlet connection 121. is located in the cap 122 on the valve casing 99 and communicates directly with the inlet valve 1000f the Operation of first embodiment The structure so far described is a fuel supply system broadly which includes'a source of fuel including a tank and a connection from the tank to a fuel pump. It also includes a recirculating circuit having a pump and apres sure regulator device connected in series withaparallel connection between the pump, the recirculating circuit, and the source- In this fuel supply system the floatandfloat valves 79 perform animporta'nt function, and,;.in. etfect,'.are one control means from the pump to either the source of fuel or the recirculating circuit. When these floats are raised and the valve 79 open, or one of them is open, as the case may be, the pump 15, is supplied with fuel from the carburetor 17 and returns that fuel to the carburetor through the metering point 57 into the overflow chamber 50 where it 'spills over the weirs into the sumps 51 or 52 and returns to the pump 15. During this stage-of the operation no fuel will be drawnfrom the fuel tank 12 orsource offuek,

After the fuel in this recirculating circuit is gradually consumed by the engine operation and the level of the 7 fuel within the sumps- 51 or 52 decreases, both valves 79 close and this source of fuel is cut olf from communication with the pump 15. The pump immediately builds up sufficient suction to draw fuel through the line 14 from the source 12, which in this case is a fuel tank, and this operation continues until the floats 7 8 or one of them again is raised to thepoint where the float valve 79 'is opened in the manner above described. This, of course, breaks the suction of the pump to the tank, and the pump is supplied with fuel from one or both of the sumps 51 and 52 until those sumps are again emptied to repeat the fuel supply cycle.

The function of the check valve 64 is primarily a precautionary one to' prevent rapid deceleration of the automotive vehicle causing a reverse flow in the line 18 back to the sumps 51 and 52. Other check valves of this nature may be included in the line 14, if desired, so as to prevent the return of fuel to the fuel tank 12. This is wholly a matter of choice or design. In the second embodiment about to be described, a selector valve performs this function, and a check valve is unnecessary.

Selector valve construction In my copending application Serial'No. 739,268, filed June 2, 1958, a selector valve has been shown located to control parallel discharge connections from the pump to the carburetor. It is also contemplated that such a selector valve can be located in parallel connections be" tween the supply line and the pump, and such a modification is shown in FIG. 7. The same reference characters will be used to indicate corresponding parts in this system which correspond with those above described in the prior modification, and the description here will be limited to the construction of the selector valve placed in the pump inlet circuits from the source and from the recirculating system, and to the manner of its operation in these circuits. In this particular embodimentshown in FIG. 7 the T-fitting 71, 72 and 73, all as shown in FIG. 2, is replaced by a similar fitting 140 connected with the return line 18 from the carburetor, the tank supply line 14, and the inlet 121 to the pump. The unit 140 includes a control valve 142 in a by-pass passage 143 interconnecting the tank line 14, the return line 18, and the inlet of the pump I21. Valve 142 has an operating diaphragm 144 secured to the valve 142 by a pair of backing plates generally indicated by the reference character 141. The diaphragm 144 divides a cavity into two chambers 145 and 146. Chamber 145 is so disposed as to form a part of the passageway leading from the suction side of the pump to the recirculating system through line 18 and tothe pump supply line 14, and is, therefore, exposed to the suction produced by the pump 15 in the chamber 145. A spring 147 exerts a very light force tending to close the valve 142 so as to cut off the supply from the fuel line 14 leading from the fuel tank. Chamber 146 has a metered connection 149 with the tank supply line 14 so as to break the suction in chamber 146 and allow the valve 142 to be moved by the diaphragrn 144 against the light pressure of spring 147.

Operation of second modification The operation of the modification shown in FIG. 7 under static conditions will be substantially the same as the prior modification. So long as the sumps 51 or 52, or one of them, is full of fuel, or contains fuel sufficient to' maintainthe valve 79 ofi its seat, the fuel will circulate in the recirculating system from the pump 15 through the overflow chamber 50 into the sumps 51 or 52, line 18, and back to the inlet of the carburetor.

When bothfloat valves 79 are closed, however, pump 15 will develop suflicient suction to move the diaphragm 144 to the right, opening the valve 142. At the same the chamber 146, so as to prevent the build-up of a force opposing the action of the pump in opening the valve 142. Since the area of the valve operating mechanism exposed to direct suction of the pump is greater in the opening direction than in the closing direction, valve142 will be maintained open, connecting the suction side of the pump- 121 with the tank supply line 14, and fuel will flow from the tank through the selector valve to the pump 15, and from there through the line 16 into the overflow chamber 50. This will continue until the floats 78, or one of them, rises, opening the valves 79, thus breaking the effect of suction on the diaphragm 144. Spring 147 will then move the valve 142 toward closed position, forcing the fuel from the chamber 146 and metered passage 149 to the tank line 14. Because of the metered passage, the movement of the valve 142 will always be gradual. Therefore, it is effective to prevent surges in the line 14 from affecting operation of the pump and flooding the carburetor through the supply line 16. In other words, a surge in line 14, being of a nature to be an instantaneous action will have a delayed eflect upon the valve 142, due to the metered passage 149, and by the time the valve starts to open, the surge is over. For this reason, the valve 64 may not be necessary, but is shown as an added precaution.

The fuel supply systems above described have many advantages in that, because of recirculation of the fuel into the fuel bowl and back to the pump, entrained vapors and gases are released and vented through the vents of the carburetor 17, not shown. The tendency of vapor lock is therefore materially reduced. Likewise, it is the tendency of an operator of a vehicle, on occurrence of vapor lock and hesitation in the power output of the vehicle, to have the instantaneous reaction of opening thethrottle, and when the throttle is opened in this system, the inlet to the carburetor fuel bowl becomes substantially unrestricted. This permits the pump to work at its full capacity against substantially no head in order to rid the system of vapor accumulation.

The use of a float valve controlled sump return line to the pump, and the operation of the selector valve above described eliminates the need for a long return line to the fuel tank, and this is true whether one or both are used. All of the above-described desirable features are obtained with both modifications.

Modified form of selector valve In this modified form (shown in FIG. 8), the valve element 142 of the prior modification has been replaced by a slide valve 150 which contains a metered bleed passage 151 for breaking the suction in chamber 146.

Certain structures have been described herein which will fulfill all the objects of the present invention, but it is contemplated that other modifications will be obvious to those skilled in the art which come within the scope of the invention as defined by the appended claims.

I claim:

1. A fuel system for an internal combustion engine of an automotive vehicle comprising an interconnected fuel tank, fuel pump and carburetor, said carburetor including a fuel bowl, an overflow chamber having a weir arranged therein to extend in the direction of travel of the vehicle for regulating the head of fuel in said fuel bowl, a fuel inlet for said overflow chamber, means for variably restricting said inlet, a sump for receiving the overflow from said chamber, an outlet from said sump, a float valve mechanism controlling said outlet, a fuel'inlet and outlet for said pump, a recirculating system between said pump and said carburetor including a connection from the pump outlet to the fuel bowl inlet and from the sump outlet time, fuel will go through the metered passage 149 into 76 to the fuel pump inlet, a supply connection from said fuel tank to said fuel pump inlet, a selector valve controlling communication between said fuel tank and said fuel pump, an actuator for said selector valve, comprising a first pressure chamber communicating with said pump inlet and said recirculating system, a second pressure 9 chamber communicatingwithsaid fuel'tank, a movable wall separating said pressure chambers, a-by-pass extend-. ing from said first pressure chamber to said selector valve, and an actuating connection between said movable wall and said selector valve whereby said latter valve is controlled in accordance with pressures at the inlet of said pump. v

2. Ina fuel supply system for. an internal combustion engine a carburetor having a mixture conduit, athrottle in said mixture conduit movable between open and closed positions, a fuelbowl, a, weir in said fuel bowl forming therewith an overflow chamber and a sump to receive the overflow from said chamber, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, means including a pump to supply fuel through said fuel inlet into said overflow chamber, and means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber.

3. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming therewith an overflow chamber and a sump to receive the overflow from said chamber, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, means including a pump to supply fuel through said fuel inlet into said overflow chamber, and cam means operable responsive to movement of said throttle for actuating said needle valves to control the flow of fuel through said fuel inlet into said overflow chamber.

4. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming therewith an overflow chamber and a sump to receive the overflow from said chamber, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, means including a pump to supply fuel through said fuel inlet into said overflow chamber, and cam means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber, said pump having an outlet connected to said overflow chamber inlet, a fuel tank, said pump having an inlet connected to said tank and said sump outlet, and means including a valve to control the flow of fuel through said sump outlet to maintain a predetermined minimum head of fuel in the sump.

5. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming therewith an overflow chamber and a sump to receive the overflow from said chamber, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, means including a pump to supply fuel through said fuel inlet into said overflow chamber, and cam means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber, said pump having an outlet connected to said over-flow chamber inlet, a fuel tank, said pump having an inlet connected to said tank and said sump outlet, and means including a valve to control the flow of fuel through said sump outlet to maintain a predetermined minimum head of fuel in the sump, and a check valve in said sump outlet.

- '6. In a fuel'supply system for'aninternal combustion engine; a carburetor having'a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming an overflow chamber and a sump, 'a fuel passage leading from the bottomof said overflowchamber to.said mixture conduit, a .fuel, inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, a fuel tank, a pumpv to supply fuel from said tankthrough said fuel inlet into said overflow chamber, and means operable responsive to movement of said throttlefor actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber.

7. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming an overflow chamber and a sump, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, a fuel tank, a pump to supply fuel from said tank through said fuel inlet into said overflow chamber, and means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber, said sump outlet being connected to the inlet side of said pump, and a float actuated valve in said sump outlet to maintain a minimum head of fuel in said sump.

8. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming an overflow chamber and a sump, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, a fuel tank, a pump to supply fuel from said tank through said fuel inlet into said overflow chamber, and means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber, said sump outlet being connected to the inlet side of said pump, a float actuated valve in said sump outlet to maintain a minimum head of fuel in said sump, and a selector valve controlling the flow of fuel from said fuel tank to said pump.

9. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming an overflow chamber and a sump, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, a fuel tank, a pump to supply fuel from said tank through said fuel inlet into said overflow chamber, and means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber, said sump outlet being connected to the inlet side of said pump, a float actuated valve in said sump outlet to maintain a minimum head of fuel in said sump, a selector valve controlling the flow of fuel from said fuel tank to said pump, means biasing said selector valve toward its closed position, and means operable responsive to lclosing of said float actuated valve to open said selector va ve.

10. In a fuel supply system for an internal combustion engine, a carburetor having a mixture conduit, a throttle in said mixture conduit movable between open and closed positions, a fuel bowl, a weir in said fuel bowl forming an overflow chamber and a sump, a fuel passage leading from the bottom of said overflow chamber to said mixture conduit, a fuel inlet for said overflow chamber, a needle valve for variably restricting said inlet, an outlet from said sump, a fuel -:tank, a =pump to supply fuel from said tank thraugli said iuel inlet into said overflow .chamber, and means operable responsive to movement of said throttle for actuating said needle valve to control the flow of fuel through said fuel inlet into said overflow chamber, said sump outlet being connected to the inlet side of said pump, a float actuated :valve in said sump outlet to maintain a minimum head of -fuel in said sump, a selector valve controlling the flow of fuel from said "fuel tank to said pump, means'biasing said selectorvalve toward its closed posi- 12 rim, and means including a dianhragm en rah resp nsive to closing of said float actuaiqi valve L0 0129. Sam selector valve. V i

ie srenses Cites in th ti I t is P IAI H ATENES 827, 549 Mauritzen July 31, 19.06 2,208,785 Armstrong July 23, 1940 2,254,850 Mallory Sept. 2, 1941 2,695,029 Bruegger s Nov. 2-3, 1954- 2,;8 183 1-1 Ross Dec. 31, 1957 

